1. Field of the Invention
The present invention relates to a turbine bypass control, and particularly relates to a turbine bypass control suitable on a turbine trip.
2. Description of Related Art
A steam pressure control on a turbine trip is conventionally carried out.
Japanese Patent Application Publication (JP-A-Heisei 7-229405) discloses a turbine bypass control method for a combined plant. The combined plant includes a turbine bypass and a turbine governor. The turbine bypass is connected to a steam turbine inlet and includes a turbine bypass valve. The turbine governor controls the turbine bypass valve. In the turbine bypass control method, when the turbine governor stops an automatic control to the turbine bypass valve, the turbine governor controls the turbine bypass valve with respect to a set pressure which is a pressure higher by a predetermined value than a turbine inlet steam pressure.
Japanese Patent Application Publication (JP-A-Heisei 11-257018) discloses a steam turbine steam bypass apparatus. The steam turbine steam bypass apparatus includes a turbine bypass valve, a sensor, a flow amount valve opening converting section and a bypass valve control section. The turbine bypass valve drains out steam from a high-pressure steam accumulator and regulates a pressure of the high-pressure steam accumulator. The sensor measures a flow of the steam drained from the high-pressure steam accumulator into the steam turbine. The flow valve opening converting section calculates an increase amount of openings of the turbine bypass valve corresponding to the measured flow amount of the steam. The bypass valve control section controls the turbine bypass valve based on a sum of the valve openings which is obtained based on the pressure in the high-pressure steam accumulator, and the calculated increase amount.